I am an Ubuntu user with Google Chrome 39.0 and whenever I enter a Google Spreadsheet-document (with Chrome), I get a warning header saying that "This version of Firefox is no longer supported, please upgrade to a supported browser".

What have I done wrong? How come Google thinks I'm using Firefox when I'm using their own browser? I have not enabled emulation in the developer tools.

When checking my user-agent at a 3rd party website, it says "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120427 Firefox/15.0a1".

  • Go to whatsmyuseragent.com. What user agent does it show?
    – user54791
    Jan 25, 2015 at 21:28
  • 1
    I have updated the question with the output from that website
    – Bob Niemöller
    Jan 25, 2015 at 21:33
  • 2
    Okay, so your Chrome browser for some reason is identifying itself to websites as Firefox 15. Do you have any extensions installed in Chrome?
    – user54791
    Jan 25, 2015 at 21:37
  • 5
    Omg, yes I have an agent-switcher extension. When I set it to "Chrome" the problem vanished... I cannot believe how stupid I was not looking for that one. Thanks for the help and sorry for the incovenience.
    – Bob Niemöller
    Jan 25, 2015 at 21:39
  • @Bob Niemöller, you are ingenious! Your post helped me solve a problem I have been googling for hours and hours ... Wonderful. Thanks for your help!
    – Henke
    Nov 12, 2020 at 17:24

1 Answer 1


Seems to have been answered by a user who does not have a Web Applications profile:

Turn an agent-switcher extension to "Chrome".

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